STRUCTURAL AND MAGNETIC-PROPERTIES OF R(FE,NI)(11.3)NB-0.7 COMPOUNDS WITH R=DY AND ER

The effect of the substitution of Ni for Fe on the magnetic and struct ural properties of RFe11.3Nb0.7 compounds (R = Dy and Er) has been stu died. All of the compounds studied crystallize in the ThMn12 type of s tructure and the lattice constants a and c decrease with increasing Ni content. Substitution of Ni for Fe leads to a clear increase of the C urie temperature and to a decrease of the saturation magnetization. Th e temperature dependencies of the ac susceptibility and the magnetizat ion indicate spin reorientations in all of the compounds. The easy-mag netization direction at room temperature has been determined to be alo ng the c-axis from x-ray diffraction patterns of magnetically aligned samples. The effect of Ni substitution on the magnetocrystalline aniso tropy is also discussed.